Categories
BLOG

brown tips on cannabis leaves

How to Prevent and Treat Dry and Crispy Cannabis Leaves

Nothing warms a grower’s heart more than seeing their plants flourish. The opposite is true when they encounter dry and crispy leaves. Such a sight causes worry and concern. Are your plants ill? Will this damage your yield? Could they be dying? We created this guide to put your mind at ease. Learn about the causes and exactly how to treat it.

How to fix dry and crispy cannabis leaves.

Contents:

Healthy and vibrant cannabis specimens dominate social media feeds. These thriving plants display firm, dark green fan leaves with a waxy shine protruding from robust and sturdy stems. Every grower strives to achieve plants that look half as healthy. However, things don’t always go to plan.

Have you ever walked into your grow space to see dry, crispy leaves hanging on for dear life? It’s disheartening, and far from the luscious foliage depicted on Instagram. If your leaves are looking a little worse for wear, check out the guide below. We’ll cover every possible cause for the condition, and how to fix it.

What Causes Dry, Crispy Cannabis Leaves?

A problem-solver lies at the heart of every cannabis grower. A large part of harvesting a canopy of healthy buds involves a fair amount of troubleshooting along the way, from nutrient deficiencies to pest invasions. Dry, crispy leaves are one of these potential problems. This occurs when plants lose their moisture content, curl up, and feel fragile and crunchy to the touch. Several environmental factors give rise to this issue—nutrient problems, too much water, and excess heat are just a few of the common culprits.

Fortunately, we’ve identified solutions to all of them. Use the guide below to learn what exactly causes cannabis leaves to turn dry, and what you can do to rescue your plants.

Old Age

Cannabis plants don’t stay young forever. Dry, crispy leaves occur naturally towards the end of a plant’s life cycle. During the late flowering stage, as plants divert most of their resources towards forming resinous buds, you’ll notice some fan leaves start to dry and discolour.

Old age largely affects the lower leaves, but those higher up might also begin to lose their moisture content and luscious green appearance. If your plants are otherwise healthy, pest-free, and enjoying ideal temperatures, chances are they are simply getting old.

Fan leaves will appear particularly dry and frail during flushing—the act of restricting feeding around two weeks before harvest to improve the flavour of the buds. An intentional lack of key nutrients will take a toll on the foliage and often cause many fan leaves to fall to the ground.

Solution

As a natural phenomenon, you have nothing to worry about. Let nature play its course. Take a clean pair of pruning shears and defoliate the dried and dying leaves to improve canopy aeration and clean up the aesthetics of your plants.

Nutrient Issues

Cannabis plants require a balance of key nutrients to survive and thrive. These natural compounds play vital roles in cannabis physiology, from assisting with photosynthesis to facilitating tissue growth and flowering.

Plants require two key groups of nutrients: macronutrients and micronutrients. As their names suggest, plants require the former in larger quantities and the latter in smaller amounts. Most growers manage to supply their plants with adequate nutrients using either high-quality compost or supplements.

Despite this, plants can still exhibit deficiency symptoms due to pH fluctuations. If the pH of the growing medium becomes too low or too high, plants lose the ability to absorb nutrients. Low levels of molecules such as iron and magnesium—important for chlorophyll formation and enzyme synthesis—can lead to crispy, dry leaves.

A nutrient surplus can also cause dry and damaged fan leaves. Excess nitrogen can burn roots, causing the fan leaves to become extremely dark green and crispy.

Solution

Adjust the pH of your growing medium to restore a healthy balance. Cannabis plants thrive in a pH of between 6.0–7.0, whereas hydroponic plants prefer a pH of 5.5–6.5. Use a pH tester to determine the status of your soil. First, attempt to flush out the growing medium with pH-balanced water and test the growing medium again. If the pH level is still out of whack, apply pH correction products available at any growing store.

Also, consider adding mycorrhizal fungi to your soil. These beneficial fungi form a mutually beneficial relationship with plant roots, helping them mine for nutrients in return for sugars.

Overwatering

It’s no secret that cannabis needs water to survive. Plants use this precious resource during photosynthesis, to transport nutrients, and to keep them turgid and strong. Yet, as with everything, too much water does more harm than good.

Overwatering usually occurs when beginner growers take too much care of their plants—they see one speck of dry soil and begin to panic. A constant supply of water means fluid begins to pool in the soil. When plants take up too much water, cells within the leaves bulge and eventually rupture. This causes crusting at the tips and a crispy complexion. Not to mention, excess water creates a breeding ground for damaging fungi, and it flushes valuable nutrients from the soil.

Solution

Water your plants intelligently. A slight dryness in the soil is actually a good thing. As a rule of thumb, only water your plant again once the top five centimetres are dry. To keep better track of things, weigh your pots when they’re dry and again when fully watered. Wait for your pots to get close to their dry weight before watering again.

Pests and Fungi

Humans aren’t the only Earthbound creatures with a penchant for pot. Many different species of microbes, insects, and mould all enjoy savouring the taste of fresh cannabis plants. Aphids, caterpillars, and slugs all like to graze on cannabis leaves, whereas plant-parasitic nematodes prefer the taste of roots. Fungi will settle just about anywhere on the plant, as long as it provides them with their favourite conditions—dampness and humidity.

Cannabis plants can take a bit of pest damage, and the presence of a few insects indicates strong biodiversity within the garden. But prolonged and intense assaults can cause them a great deal of stress, possibly resulting in dry and crispy leaves.

Solution

Protect your plants! Different species require different tactics. Use predatory insects such as ladybugs, parasitic wasps, and praying mantis to keep pest species at bay. For a second line of defence, sow companion plants such as dill, sweet basil, sunflower, and lavender early in the season to repel and distract damaging insects.

Do you have a feeling your roots are under attack? Inoculate your soil with mycorrhizal fungi; their fine filaments—hyphae—tie down and trap gnawing nematodes. And what about that pesky mould? Simple. Keep your plants aerated with fans or a natural breeze. Avoid overwatering the soil and cover up your crop to protect it from downpours during flowering.

Excessive Heat

Heat has a tendency to make things crispy: bacon, toast, even our skin after too much time on the beach. Leave your cannabis plants exposed under the baking sun in a greenhouse or garden, and you’ll find their fan leaves take on this property, too. Intense heat will cause leaves to lose moisture, dry out, and shrivel up.

Solution

If you’re growing outdoors in a particularly hot region, be prepared to defend your plants from a heatwave. Keep some shade cloth and a few stakes on standby, and deploy a DIY setup if the sun beats down harshly for too long.

If you find your grow room becomes unbearably hot, use fans and air conditioning to bring the temperature down. You can even use a sensor and controller rigged up to an exhaust fan to automate this function.

Light Burn

Another pillar of plant life, light enables cannabis plants to create their own energy. Without light, you can say goodbye to cannabis buds altogether. Yet, too much light will burn the upper areas of your plant, causing leaves to crisp over and even damaging high-flying colas. If you let your canopy grow too tall, expect discolouration, dryness, and reduced yields.

Solution

Monitor your indoor grow closely. Move your light system up as your plant continues to work its way upwards. If you’re dealing with limited space, use LST and Sc rOG techniques to keep your canopy lower to the ground without sacrificing output.

LED lights are becoming more popular among cannabis growers. As well as being cheaper to run, these lights emit less heat and offer more room for error if your plants grow a tad out of control.

Treating Dry, Crispy Leaves on Weed Plants

If you notice fan leaves becoming crispy and dry, don’t panic! Take on the problem with a level head and remember what you’ve just learned. Revisit our guide, identify the prob lem, and utilise the correct treatment. If you act efficiently, you’ll rescue your plants, solve a horticultural problem, and become a better grower all at the same time.

Dry and crispy leaves don't just look bad, they can stir up quite a panic. But don't worry, check out our guide to discover every single cause and treatment.

Nutrient Burn

Quick Summary: Nutrient burn or fertilizer burn is one of the most common beginner cannabis growing problems. The yellow or brown leaf tips are caused by too-high levels of nutrients at the roots, which disrupts the flow of water through the plant and causes the symptom of burnt tips on leaves.

(Nutrient burn is often called “Nute Burn” in the cannabis growing community).

When the roots take in more nutrients than a cannabis plant can use, the overabundance causes problem with water flow in the plant, triggering brown or bronze “burns” on the tips of your leaves. If nutrient levels are not lowered, the burnt tips start traveling inwards and the ends of leaves start becoming crispy and twisted.

As nutrient burn progresses, the tips start getting bronze, crispy, curled and sometimes twisted. Although you can stop nutrient burn from getting worse, the burnt appearance won’t go away on the leaves that were already affected.

Nutrient burn is most common when feeding cannabis too-high levels of bottled nutrients and especially chemical or mineral nutrients. This is what you’ll find in most non-organic plant food.

Mineral-based nutrients can help increase cannabis growth rates and yields compared to organic-based nutrients due to the fact that these nutrients are so easily absorbed by the plant roots. The plant doesn’t have to do any “work” to get the nutrients. The downside is your plant can easily take in more than it can use if the nutrient levels are too high.

Nutrient burn affects the tips of marijuana leaves. You may just see it on one or two leaves, or it can appear all over the plant.

Nutrient burn can also happen when plants or seedlings are grown directly in soil that has a high level of nutrients (a “hot” soil or growing medium) such as fresh compost, manure or a nutrient-amended soil mix. This usually happens to young seedlings, and they will “grow out of it” as they begin to use up all the nutrients in the soil, as long as more nutrients are not added.

In general, plants use overall higher levels of nutrients as they get more light. Therefore plants in relatively low light conditions can get nutrient burn at lower levels of nutrient than the same plant would under bigger grow lights.

Each cannabis plant is different, so you might have just one out of many plants get nutrient burn! That is completely normal.

Sometimes you’ll also see nutrient burn leaf tips also curl or “claw”. The clawing can be caused by an overabundance of Nitrogen (Nitrogen Toxicity), which is common for plants that are experiencing nutrient burn from overall high levels of nutrients.

Problem: You will notice the tips of your marijuana leaves showing the first signs of nutrient burn by turning yellow, tan, gold or brown. A light case of nutrient burn will only affect the tips of your leaves.

The yellow tips will eventually turn rusty brown and crispy. If you do not correct the problem, you may also notice the burn slowly spreading from the tips to the whole leaf. At this point, if you haven’t done so already, you should immediately treat your plant (directions below) before there’s more damage.

Nutrient burn can also manifest itself as brown or bronze spotting around the edges of the leaf serrations (often when there’s a problem with proper absorption of potassium), or with leaf tips curling downwards (tips pointing down is often associated with too much nitrogen).

Nutrient burn causes tips to start curling up if it gets bad enough

These Are NOT Nutrient Burn!

(Sometimes Mistaken for Nutrient Burn)

Light Stress can cause yellow tips or edges, which can sometimes be confused with nutrient burn

This is actually a Potassium Deficiency, not nutrient burn!

Why Growers Should Try to Prevent Marijuana From Getting Nutrient Burn

I have heard some growers say that a little nutrient burn is actually a good thing, because it means that you are giving your plant the highest level of nutrients it can use. A lot of growers have the mistaken idea that nutrients are somehow “food” for your cannabis plants, and so more food = more energy = bigger yields.

This is wrong, instead nutrients are more like a multi-vitamin for your plant. Just like you can’t give a child 10 multivitamins a day to make them grow faster, you can’t give your plants 10x the regular does of nutrients and expect anything good to happen.

The real “food” for your plant is light. Your plant produces energy from light through a process known as photosynthesis, which is most effective when the plant has healthy green leaves.

Your leaves are like solar panels, and the energy produced by the leaves is used as energy for the whole plant. You need the leaves to be in tip-top shape to get the most energy from the lights, so your plant has plenty of energy to grow and produce buds.

Therefore, the biggest problem with nutrient burn is the fact that you are losing leaf mass and overall leaf robustness on your cannabis plant.

A little nute burn won’t slow down your plants much, if at all, but if nute burn is left out of control, you will begin to lose serious leaf mass and it will dramatically slow down plant growth and reduce your overall yields.

What’s worse, if excess nutrients are not flushed out of the plant’s system before harvest, the buds may contain trace amounts of extra nutrients, giving the buds an unpleasant chemical-like taste. Speaking of the flowering stage… (Wait, what’s the flowering stage?)

Nutrient Burn is More Serious in the Flowering Stage

Cannabis plants spend the beginning part of their life in the vegetative stage. When cannabis plants enter the second part of their life, the flowering stage, they stop focusing on making leaves and stems, and put all their focus on making buds/flowers.

The flowering stage is the most vulnerable stage for cannabis plants, because they don’t have much ability to bounce back from any problems.

The further you get into the flowering stage (and the closer you get to harvest), the less likely the plant will replace a leaf that is damaged or dies. By the time harvest is around the corner, your plant basically stops making any effort to recover from leaf damage, and its complete focus is on fattening buds.

That’s why budding cannabis plants need extra care to thrive – in the flowering stage, a little bit of nutrient burn will probably be okay, but too much nutrient burn can seriously hurt yields because the plant will not be able to recover. If you are adding nutrients to your water, it can be very easy to burn your plants in the flowering stage (even with nutrient levels it was fine with before) as different strains have different needs throughout budding.

Solution to Cannabis Nute Burn

If you are using bottled nutrients – Most people who get nute burn are feeding their plants extra nutrients in the water. First off, make sure you are using a quality set of nutrients that has been specifically designed for cannabis plants. Any nutrient system designed for plants like a tomato will also work in a pinch. Also make sure you are feeding nutrients for the right growth stage – for example, all cannabis nutrient systems have you feed different nutrients for the vegetative and flowering stage. If you are feeding the wrong type of nutrients for the stage your plant is in, that is an easy way to give your plants lots of nutrient problems including nutrient burn.

If you are using the wrong type of nutrients for a plant like cannabis, you will eventually run into nutrient problems, one way or another.

Many nutrient systems come with instructions to feed your plant more nutrients than most plants actually need. It’s good business for the nutrient companies if you use more nutrients. However, in my experience it’s a good idea to view the feeding charts that come with any nutrient system as the maximum amount of nutrients and actually start with much lower levels. I tend to start with half the recommended amount, and slowly work my way up only if needed.

Hand-watered system – If you are growing in a handwatered system (like in soil or coco coir), flush your system with plain, pH’ed water if you notice the first signs of nutrient burn. (Learn about pH). If you are not adding any extra nutrients in your grow, then you simply need to wait until the plant uses all the excess nutrients in the soil – after the nutes have been used up, the plant will naturally get over the nute burn (old leaves won’t recover, but leaves should no longer be getting new brown or burnt tips).

Hydro system – Reduce the overall levels of nutrients in your water reservoir by either adding plain pH’ed water to dilute the water, or you could also mix up a new set of nutrients (at lower levels) and completely change the water.

Be careful not to make big changes too fast, it’s better to go relatively slowly in hydro.

In hydro, once you change the water and lower the nutrient levels to an appropriate level, you should immediately notice the nutrient burn stop spreading. Old leaves won’t recover, but you shouldn’t notice any leaves getting worse.

If you don’t have a TDS meter to measure the levels of nutrients (and other extra stuff) in your water, I would normally start your plants with a fraction (perhaps 1/2) of the nutrients you were giving them before – and then work your way up to higher nutrient levels only if you notice the lower leaves are starting to yellow too quickly (nitrogen deficiency). Even then, try to move up nutrient levels as slowly as you can. If you lose leaves to a nitrogen deficiency from slightly too-low nutrient levels, you will lose a few of the least important lower leaves. But if you raise nutrient levels to fast and get nutrient burn, all the leaves on the whole plant will be affected and never recover fully.

One of the things that can be frustrating about hydro is that different plants or strains will be okay with different amounts of nutrients. You can be giving 2 plants the exact same levels of nutrients, and one might get nutrient burn while the other plant is getting a deficiency at the same level. This is because different plants absorb the nutrients at different rates.

Plus, plants drink more or less water depending on the temperature and humidity of your grow area, so even if you’re familiar with the nutrient levels of a particular strain, it can be hard to keep track of the exact right nutrient levels until you get familiar with your setup, unless…

Luckily, there is an awesome tool to make this much easier in hydro.

In hydro, it is very helpful to get a tool called a TDS meter to help you regulate the amount of nutrients in your water. A TDS meter will be able to tell you how much “stuff” is in the water, and whether the levels of nutrients are getting higher or lower each time you check. You can test your reservoir at any time to see if the levels of nutrients are rising, so you’ll be able to stop nutrient burn before it even affects your plants.

To find out more about using a TDS meter to measure nutrients in your water, check out our article: PPM: What It Is and How To Track It.

Could your cannabis also be suffering from Nitrogen Toxicity? – Nitrogen toxicity is common on cannabis plants with nutrient burn

Are the ends of leaves curling like a claw or pointing down like talons? If your plant is experiencing “the claw” and not just normal drooping like from underwatering or overwatering, then you may have a nitrogen toxicity (too much nitrogen).

These Plants Are NOT Overwatered, These Leaves Show Signs of Nitrogen Toxicity

Learn more: Nitrogen Toxicity
(“The Claw”, tips bent down, curling / clawing, dark green leaves)

Nitrogen toxicity is relatively common with plants experiencing nutrient burn.

Nutrient burn causes the tips of cannabis leaves to turn yellow or brown. The burnt tips are the result of too-high levels of nutrients. Learn how to fix it! ]]>